System of motor control.



E. KRAUSE.

SYSTEM OF MOTOR CONTROL. APPLICATION FILED APR. 11, 1911.

Patented May 7, 1912.

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v e 2 s n him. a 0 POD. n M S H m Em Witnesses UNITED STATES PATENT orrron.

EDMUND xnausn, or WAIDMANNSLUST,' GERMANY, ASSIGNOR- T GENERAL ELEC- ran: COMPANY, A CORPORATION or NEW YORK,

tems of control of electric motors used for the voltage of generator A and thereby the speed of the motor C. The resistance E may {be automatically regulated in any well- SYSTEM OF MOTOR CONTROL.

Y Application filed April 11,1911; Serial-No. 620,351.

To all whom it may concern.-

6 certain new and useful Improvements in Systems of -Motor Control, of which the following is a specification.

My invention relates to motor control systems and is particularly applicableto syshoisting and .the like.

The system frequently used for hoists comprises the. speed controlof a direct cur-; rent motor with a constant field excitation. by varying the voltage of a separately ex-;

cited generator supplying the motor armature. In such systems the speed of the motor is not always the same for corresponding positions of the controller as, for instanceg 39 the speed inhoisting a load is often lower for a position of the controller than thespeed in lowering for a corresponding posi-' Because of this vari-; ation in speed, the stopping of the hoist .22 at the same point of its travel with different tion of the controller.

' 'loads'becomes very ditficult.

M invention'has for its object to obviate this .diiiiculty by controlling the speed ofthe motor so that it .is substantially the same: for the. same or corresponding positions Off the controller. p

The various features of novelty, which characterizemy invention, will be pointed outwith particularity in the claims annexed 'to andforming. a part of this specification.

For a better understanding of my invention, reference may be had tothe following description taken in connection with the accompanying drawing in which the single 'figure'shows diagrammatically a control system in accordance with my. invention.

In the drawing, A represents the armature and a thefield winding of a separately ex- .cited' generator.

. B represents a separate exciter, which may consist of any suitable source of current, for instance, of a small generator, as shown, suitably driven.

C represents the armature of a motor supplied with current from the armature A of switch, which is arranged to connect the the generator and 0 represents the field winding of the motor supplied with constant excitation from the exciter B. D represents. a controller, or control Specificationlof Letters Patent.

. direction.

'PatentedMay 7, 1912. I

generator field winding a to the bus-bars L, which are suppliedwith-current from the exciter B, through the resistances (Z or cl andthe reversing switch 6 and thereby vary and reverse thefcurrent supplied to the generator field winding. This control switch also performs other functions hereinafter to be described. e

In series with the generator field winding a is a resistance E which serves to correct known manner, but I have preferred to regulate it by means of a motor F. The motor ;'F is connected-in circuit for one or the other direction of, rotation, when the speed of the motor varies from .its normal value, by means'of a contactl'device or relay G.

The relay G preferably consists of a magnet having two of its arms excited by windings g and g in'such a manner that at their ends like poles are formed, as. for example, two north poles N and N. The third arm 'h of thisrelay is pivotally mounted and has l a contact arm 2' arranged to make contact with" one or the other adjustable contacts lcorf'ls': As long as the excitation of the windings g and g are substantially equal,

the arm h is heldin its middle position by the springs rm-and m, in which positionit plays freely between contacts In and If one or the other excitation preponderates, the armh is deflected to one side or the other, whereby the armature of the motor F is connected in circuit in one or 'the other As shown in the drawing,'the relay Gr operates the contactors O or O, which, in turn, close the circuit of the motor F in one or the other direction. In order to increase the sensitivenessof the contacting device or relay G at low speeds of the motor C, an additional excitation is provided. The winding 7) serves this purpose "and is disposed on all three arms of the magnet, assisting the windings g and g on the outer arms tocreate north poles, for ex ample, and creating a free pole of the opposite polarity on the inner arm. Thewin-ding 9 is preferably connected across the terminals of the motor armature C through a reversing switch 1- upon the controller-1?. By thus connecting the winding 9 this excitation is substantially proportional to the speed of the hoist motor and would be ex resistance.

' the motor F remains at rest.

g preponderates,

,actly in proportion to the speed of the hoist motor, it it were not tor the fall of potential in the motor armature due to its It would be possible to have the excitation of the winding 9 exactly proportional to the speed of the-motor'by connecting it up in a well-known manner to an exclter driven by the motor.

is excited from the busses L through one or the other of the variable resistances s or s,- one or the other, of which is varied, and cut in or out by the controller D. I

O. The energiz'ation of one of these re lays connects the motor F in circuit by bridging the contacts t and u, or t and u, and thereby cuts in or out more or less of the resistance E in series with the field winding (2 of the generator, which weakens or strengthens the excitation of the generator and consequently afi'ects the speed of the hoist motor. 'Ihe resistance E is connected in the generator field circuit in such a way that the excitation of the field winding a is reduced it the speed of the hoist motorexceeds the normal value, andis increased it the speed or the hoist motor is less than the normal value. -'Ihe motor F continues to operate until the hoist motor C again reaches normal speed, when the exci-- tations of the relay winding g and 9 again become equal and the contact arm 2' leaves the contact upon which it has rested, opening the circuit of the motor F. q 1

I desire to be understood that my invention is not limited to the specific arrangement of circuits shown and described, and I aim in the appended claims to cover all modifications which do not divert from the spirit and scope of my invention.

What I claim as new and desire to secureby Letters Patent of the United States, is,-

1. In combination, a motor, a generator supplying-said motor, a controller for varying the field strength of the generator to vary the voltage supplied to said motor, and means for maintaining the speed of the motor substantially the same for the same or corresponding positions of the controller.

2. In combination, a motor, a generator supplying said motor, a controller for varying the field strength of the generator to vary the voltage supplied to said motor, and

Winding g I and 7c, and

means depending on the speed of said motor for maintaining the speed of the motor substantially the same for the same orcorresponding positions of said controller.

3. In combination, a motor, a generator supplying said motor, a controller for varying the field strength of the generator to vary the voltage supplied to said motor, a relay for varying the resistance in the field circuit of said generator depending upon the speed of said motor.

4. In combination, a motor, a generator supplying said motor, a controller for varying vary the voltage supplied to said motor, and a relay for varying the resistance in the field circuit of said generator'comprising a coil connectedacross the armature of said motor.

and

the field strength of the generator to 5. In combination, a motor, a generator supplying said motor, a controller for vary ing the field strength of the generator to vary the voltage supplied to said motor, and

a relay for varying the resistance in the field circuit of said generator, said relay having a coil connected across the armature of said motor and another coi'l connected in series with a variable resistance across a constant source of excitation.

6.. In combination, a motor, a generator supplying said motor, a relay for varying the resistance in the field circuit of said generator, said relay having a coil connected across the armature of said motor and another coil connected inseries with a variable resistance across a constant source of excitation, and a controller for varying the field strength of the generator to vary the voltage supplied to said motor, to reverse said mo- 1 tor, to reverse said coil of the relay connected across the armature of said motor, and to vary the resistance in seriesw'ithsaid other coil-of the relay.

7. In combination, a motor, a generator supplying said motor, a controller for varying 'the field strength of the generator to vary the voltage supplied to said motor, and means for varying the resistance in the field circuit of said generator comprising a-coil connected across the armature of said motor. 8. In combination, a motor, a generator supplying said motor, a controller for varying the field strength of the generator to vary the voltage supplied tosaid motor, and means for varying the resistance in the field of said generator, said means having a coilconnected across the armature of the said motor and another coil co nected in series other co1l connected in series with a variable tion, and a controller for varying the field strength of the generator to vary the voltage and to vary supplied to said motor, to reverse said motor, to reverse the coil of said means connected-across the armature of said motor, the resistance in series with the I other coil of said relay.

' 10. In combination, a separately excited motor, a separately excited generator supplying said motor, a controller for varying the field strength of the generator to vary the voltage supplied to said motorand to reverse said motor, and means for varying the resistance inthe field circuit of said generator depending upon the speed offsaid motor.

11. In combination, a separately excited:

mot-or, a separately excited generator supplying said motor, a controller for varying the field strengthpf the generator to vary I the voltage supplied to saidmotor and to "reverse said motor, and means for varying.

the resistance in the field circuit of said generator comprising a coil connected across the armature of said motor.

7 12. In combination, a separately excited motor, a separately excited generator supplying said motor, a controller for varying the field strength of the generator to vary the voltage supplied to said motor and to re verse said motor, and means for varying the resistance in the field circuit'of said. generator, said means having a coil connected across the armature of said motor and another coil connected inseries with a variable resistance across a constant source of excitation.

In witness whereof, I have hereunto set my hand this 27th day of March, 1911.

EDMUND KRAUSE. Witnesses: i

WOLDEM R HAUPT, HENRY HAsrnn, 

